I. Field of the Invention
The present invention relates to brakes for motors and, more particularly, to the mechanisms for applying and releasing brakes.
II. Description of the Prior Art
Spring applied, magnetically released brakes are broadly known in the art. For example, U.S. Pat. No. 4,181,201 shows a spring applied, electromagnetically released brake mechanism in which a compression spring is attached to one end of an elongated brake lever opposite from the hinge point of the brake lever. The brake lever, adjacent to the hinge point of the brake, operates a brake shoe which engages a rotatable brake disk and brings the disk into and out of engagement with a fixed brake plate mounted within the housing. A solenoid is mounted between the hinge point of the brake lever and the compression spring. The solenoid is connected via a cam linkage to cause pivotal movement of the brake lever.
U.S. Pat. No. 4,042,077 shows a spring applied, electromagnetically operated hydraulic released brake. U.S. Pat. No. 4,022,301 shows a spring applied, electromagnetically released brake which includes a cam and cam followers to move a brake lever about one end coaxial with the spring. The spring and the brake lever cooperate to apply force on the floating jaw which drives the floating jaw and the intermediate brake pad into engagement with a fixed jaw, thereby preventing the brake disk from rotation. A solenoid which operates the cam is located outside of the spring and the fulcrum point of the brake lever. U.S. Pat. No. 3,556,266 shows a spring applied, electromagnetically released brake, wherein the entire brake plate is moved in and out of engagement with the brake disk.
U.S. Pat. No. 3,525,424 shows a spring applied, electromagnetically released brake where a solenoid acts on the brake lever at its free end opposite from the hinged end. The spring is positioned closer to the hinged end than the solenoid. U.S. Pat. No. 3,500,971 shows a spring applied, electromagnetically released brake where a solenoid acts through a series of links, camming rollers and brake lever. The brake lever is pivoted about a hinged connection. U.S. Pat. No. 3,221,845 shows a spring applied, electromagnetically released brake where a solenoid acts through a rocker arm which is connected to a cam shaft interacting with a yoke lever. The yoke lever pivots about two conventional ball bearings disposed between the yoke lever and the mounting plate. U.S. Pat. No. 3,171,515 shows a spring applied, electromagnetically released brake where the solenoid is mounted outboard of the spring which is centrally aligned on a common axis with the motor shaft. A pair of mating disks and rings are brought into and out of engagement by movement of an armature to energize or deenergize the motor.
Electromagnetically applied, spring released brakes are also broadly known in the art. For example, U.S. Pat. No. 3,878,922 shows an electromagnetically applied, spring released brake where a solenoid acts through a linkage assembly to apply the brake lever arm. The springs release the brake when the solenoid is deenergized by returning the linkage assembly to a rest position. U.S. Pat. No. 3,858,700 also shows an electromagnetically applied, spring released brake where the brake disk is an armature which is drawn toward a magnetic winding when energized, causing frictional forces to occur between the face of the armature and the face of the magnetic body. The armature is released by springs when the magnetic winding is deenergized.
None of the above-identified patents disclose a continuous frame member with a fulcrum which is located on the opposite side of the lever from the side of the lever facing the brake disk, nor is a frame member disclosed which supports the electromagnetic means, for direct connection with the brake lever without linkage or cam assemblies, and also supports the spring means, between the frame member and the brake lever, positioned further than the electromagnetic means from the fulcrum, allowing use of a long, low spring-rate design and eliminating the need for spring adjustment. Furthermore, it would be advantageous to locate the electromagnetic means and the pressure point on the brake pad between the fulcrum and the spring means, so that the force on the fulcrum is always in the same direction, thereby eliminating the need for a hinged connection on the brake lever which is used in some of the disclosed art.